Preparation And Photocatalytic Properties Of Semiconductor Materials By Dealloying Method

Cu₂O is a potential semiconductor photocatalysts which have a high efficiency of theoretical photoelectric conversion and can be activated by the visible light,non-toxic and low-cost,but Cu₂O have some troubles such as easy to be inactivation,low efficiency of catalysis.In this thesis,we fabricate the Cu₂O semiconductor composite to solve that problem by dealloying amorphous alloy,and the fabrication of progress which affect sample were studied and summarized as follows.Cu-Zr amorphous alloys were used to synthesize samples by dealloying.By changing synthesis parameters?the composition of precursor,the type of solution,the reaction temperature,the reaction time?,we can get different products.Results show that Cu₅₀Zr₅₀ samples have the biggest specific surface area of 20.49 m²/g,and have uniform porous structures.Amorphous Cu₅₀Zr₅₀ alloys only react with HCl.The higher the reaction temperature,the weaker the broad diffuse diffraction peak and the stronger the diffraction peaks of Cu.Cu₂O can be produced just at room temperature.With extended reaction time,diffraction peaks of Cu₂O gradually enhanced,10 h sample is the strongest one.And 10 h sample owns the best catalytic properties which removes MB 70%after 2 h,K is 0.0143 min^-1.10 h sample still maintain 70%degradation efficiency after 50 cycle.Different morphology,structure and phase can be synthesized by dealloying of Cu-Ti amorphous alloy and thermal treatment,and the experimental parameters that affect samples were studied.Results show that the more the content of Cu in Cu-Ti amorphous alloys,the stronger the diffraction peaks of Cu₂O and the weaker the intensity of TiO₂.Sample dealloyed using Cu₄₀Ti₆₀ amorphous alloys displays the best photocatalytic properties,that is,MB can be removed 97%only for 80 min,K is0.0632 min^-1.From XPS analysis,it is known that sample is composed of Cu?Cu₂O and TiO₂ after dealloying of Cu₄₀Ti₆₀ amorphous alloy and heat treatment,and a little of CuO can be found after degradating MB.Changing the reaction time,the 18 h sample is a porous structure which consists of nano-particles,nanolines and nanorods,and the samples of 9 h,12 h,15 h,18 h own excellent photocatalytic properties which degrade MB from 100%to 4%in 60 min.The surface phases are composed of Cu,TiO₂,Cu₃Ti₃O at 5 Pa.They evolve to Cu,Cu₂O,TiO₂ at 0.098 MPa and Cu,CuO,TiO₂ in air.The photocatalytic property of 0.098 MPa sample is better than that of 0.1MPa,and the 5 Pa is the best.The time of thermal treatment is prolonged which results in Cu,TiO₂ to transform into Cu,Cu₂O and TiO₂.And sample of 3.5 h is the best which remove MB 96%after 1 h,K is 0.061 min^-1.The phase of Cu₄Ti₃,Cu,TiO₂ translate into Cu₂O,Cu,TiO₂ due to increase in the concentration of HCl.And morphology of sample is from porous structure to sclausura structure.The 2.4 mol/L sample is the best,as MB can be degraded to 4%after 1 h,in which K is 0.052 min^-1.After 10 cycles,the sample still maintain 89%degradation efficiency.Under the visible light,sample removes MB 85%after 80 min which is the best compared to Cu₂O and TiO₂.Under simulated sunlight,the catalytic property of sample is better than Cu₂O,but lower than TiO₂.